Antenna structure

Abstract

An antenna structure includes a ground plane, a first radiation element, a second radiation element, a third radiation element, a fourth radiation element, and a dielectric substrate. The first radiation element has a feeding point. The second radiation element is coupled to the feeding point. The non-metal region is substantially surrounded by the first radiation element and the second radiation element. The third radiation element is coupled to a first shorting point on the ground plane. The third radiation element is adjacent to the first radiation element and the second radiation element. The fourth radiation element is coupled to a second shorting point on the ground plane. The fourth radiation element is adjacent to the second radiation element. The ground plane, the first radiation element, the second radiation element, the third radiation element, and the fourth radiation element are all disposed on the dielectric substrate.

What is claimed is: 
     
       1. An antenna structure, comprising:
 a ground plane; 
 a first radiation element, having a feeding point; 
 a second radiation element, coupled to the feeding point, wherein a non-metal region is surrounded by the first radiation element and the second radiation element; 
 a third radiation element, coupled to a first shorting point on the ground plane, wherein the third radiation element is adjacent to the first radiation element and the second radiation element; 
 a fourth radiation element, coupled to a second shorting point on the ground plane, wherein the fourth radiation element is adjacent to the second radiation element; and 
 a dielectric substrate, wherein the ground plane, the first radiation element, the second radiation element, the third radiation element, and the fourth radiation element are disposed on the dielectric substrates; 
 wherein the second radiation element comprises a first segment and a second segment coupled to each other, and an obtuse angle is formed between the first segment and the second segment. 
 
     
     
       2. The antenna structure as claimed in  claim 1 , wherein each of the first radiation element and the fourth radiation element substantially has an L-shape. 
     
     
       3. The antenna structure as claimed in  claim 1 , wherein the third radiation element comprises a third segment and a fourth segment coupled to each other, an acute angle is formed between the third segment and the fourth segment, and a sum of the acute angle and the obtuse angle is substantially equal to 180 degrees. 
     
     
       4. The antenna structure as claimed in  claim 1 , wherein the antenna structure covers a first frequency band, a second frequency band, and a third frequency band, the first frequency band is from 700 MHz to 960 MHz, the second frequency band is from 1710 MHz to 2200 MHz, and the third frequency band is from 2400 MHz to 2700 MHz. 
     
     
       5. The antenna structure as claimed in  claim 4 , wherein a first coupling gap is formed between the third radiation element and the first radiation element, and a second coupling gap is formed between the third radiation element and the second radiation element, such that the third radiation element is excited by the first radiation element and the second radiation element using a coupling mechanism, and wherein a third coupling gap is formed between the fourth radiation element and the second radiation element, such that the fourth radiation element is excited by the second radiation element using a coupling mechanism. 
     
     
       6. The antenna structure as claimed in  claim 4 , wherein a length of the first radiation element is substantially equal to 0.25 wavelength of a low-frequency portion of the second frequency band, and the low-frequency portion is from 1710 MHz to 1800 MHz. 
     
     
       7. The antenna structure as claimed in  claim 4 , wherein a length of the second radiation element is substantially equal to 0.25 wavelength of a high-frequency portion of the second frequency band, and the high-frequency portion is from 1900 MHz to 2200 MHz. 
     
     
       8. The antenna structure as claimed in  claim 4 , wherein a length of the third radiation element is substantially equal to 0.25 wavelength of the first frequency band. 
     
     
       9. The antenna structure as claimed in  claim 4 , wherein a length of the fourth radiation element is substantially equal to 0.25 wavelength of the third frequency band.